Acute leukemia, non-Hodkin's lymphomas (especially Burkitt's lymphoma), neuroblastoma, rhabdomyosarcoma, osteogenic sarcoma, histiocytosis and aplastic anemia are studied. In leukemia, we hope to devise effective therapeutic regimens which allow maximum tumor cell kill with chemotherapy and immunotherapy, while leaving intact the immune response. In the solid tumors, we hope to develop combined modality approaches to primary (nonmetastatic) disease. In previously treated (refractory) tumors, our objective is to study the role of high-dose ablative therapy, and the role of supportive care (platelet and white cell-transfusion, laminar-flow protection, bone marrow rescue) in permitting such ablation. Phase I trials are also conducted in refractory tumors; agents include maytansine and poly I:C/poly-1-lysine. Research on histiocytosis is concerned with disease mechanisms. Aplastic anemia is studied as a model for bone marrow regeneration kinetics and supportive care techniques. Studies are carried out on the biology of selected tumors, including kinetics, immunology, virology, markers, genetics, and biochemistry. Also studied are the short- and long-term effects of malignant disease and its treatment on growth and development. The psychosocial concomitants of cancer in patients, their families and their therapists are being explored.